@Brian FitzGerald
Hey Brian, my take is it's a case by case basis. Since you mentioned your friend is not sending the particular listings you are referring to, it in my opinion opens up some scenarios. I believe in the saying "take care of people and they will take care of you". In a scenario you described my top investor customer would likely tell me something along the lines of "Shawn you've put so much $ in my pocket I want you to get paid." He also knows I'm going to aggressively hands on deal with any BS that comes up.
I have other investors that maybe have used me for a deal or two and trust my opinion,-and may just want to run the property by me to see if their thoughts match mine. After I throw in my two cents worth, I've had it where that buyer then went with offering through the listing agent and didn't involve me further. I've also had it where if it was a for sale by owner or distressed property they proposed that they want my help,-but since they found the deal and put it in my lap, they then negotiate a flat fee or maybe I handled the transaction for just 2%. (As an agent there are times I'd pass on this proposition, but I also have to look at how much business have they already done with me and how likely are they to do more business with me in the future.)
Next, the question you have about the commission being reduced through the listing agent is not necessarily cut and dry. Many times like some posters have mentioned,-there is a set commission the seller is going to pay regardless. Oftentimes however, myself and other agents that deal with a lot of investment properties take what is referred to as a variable rate commission. For example, let's say the total commission is 6%, but if the listing agent sells the property him or herself, that commission can be reduced to say 4.5%. So yes, there is sometimes some flexibility in the commission if you go through the listing agent.
Some things to keep in mind however: though the high percentage of Realtors are ethical, there are the sleaze balls that would would shake down their own mother for a nickel. It's one thing if you were to go to a listing agent directly (assuming you had not already looked at the listing with your own Realtor) and you propose making a slightly lower offer based on the premise that the listing agent can either make more commission, or at the very least make the sale and be able to reduce the commission somewhat to make the deal work. If however, the listing agent is encouraging to ditch your Realtor for the transaction to get a "better deal", keep in mind that agent is selfish. That agent in that case has first loyalty to himself or herself, not the seller or you. -and when doing business with an untrustworthy person,-you may or may not get a better deal when the dust settles.
I'm going to also touch on what another agent mentioned. Value. If you value the relationship you have with your friend/Realtor, you also have to look at how much they bring to the table past, present, and future. If every now and then you find a deal and don't involve your friend/Realtor, that is your business. The dynamic may be that your friend doesn't care if you're not asking them to work pro bono. On the other hand, if it turns into a complicated deal, (inspections turn up items that could be roadblocks/deal killers, or something comes up because the lender you're using underwriters don't understand something about a property or neighborhood and it may kill the deal etc)-great Realtors are constantly guiding customers and finding solutions. You may or may not be experienced enough to handle these curve balls. I don't know you. That being said, a good Realtor will sometimes provide you with the value of the 3% with the results they produce in negotiations both upfront and during the inspection period. For that matter, they can sometimes find ways to save deals that otherwise look to be dead.
In conclusion, here are the bullet points.
1. Sometimes you may get a better deal & sometimes the commission is negotiable.
2. Case by case basis. If the Realtor is a friend that you think of to help you buy and sell your personal residence but isn't necessarily a pit bull when it comes to investment properties,-maybe you may be better off in that case either finding a buyers agent for investment properties, or like you mentioned,-just got directly to the listing agent. (Note, it's luck of the draw whether the listing agent will be 100% on the up and up with you or not.) If however your friend consistently brings value, try to look at the big picture. This doesn't definitively mean you have to cut them in on that particular transaction,-but try to not make a short sighted decision. Win/win mentality.
3. Get your Real Estate license. On the one hand I think with your mindset you'll appreciate the value you get from saving on the commission & will have access to the local MLS with the Private Realtor remarks which sometimes makes things more convenient. On the other hand, I think you'll also over time begin to have a slightly higher level of respect for what some agents bring to the table. You might have some in your sphere of influence that want your help as their agent.